Over the Logos4+ years (I guess, maybe 13 years?), I've seen the 'rebuild index' idea go back and forth, like the ocean tide. Typically staff was the 'waste of time', forum non-experts 'definitely!', and in-between 'depends'.
I loaded Verbum on my new MBP, a couple of months back; no resources. Then I selectively downloaded what I wanted. I'm guessing I've downloaded maybe 2/3's. Not all at once.
Today, I wanted to see more on 'Nora Stone'. It was discussed in the journal I was reading (odd fact ... name the non-Israel location most mentioned in the OT).
But my basic-search could barely find it. And not in the journal I was reading.
So I did a 'rebuild index' for the first time in 13 years. Took a bit to trick the command box. But an hour later, done! And now Nora Stone is well attested in my library.
I doubt 'rebuild index' is a common solution. But apparently 'indexing' isn't that reliable with segmented downloads?